The government’s critics have hit back at suggestions that cutting prison sentences would be a “reckless” and potentially dangerous response to the growing problem of violence and overcrowding in UK jails.

In a speech today, the Justice Secretary Liz Truss dismissed calls to use shorter sentences as a means of reducing surging prison populations, arguing that this approach threatened to “endanger the public”.

She instead set out longer-term plans to toughen up community sentences and boost prison staffing levels, while placing a greater emphasis on offender rehabilitation.

But MPs who have campaigned for sentencing reforms – including the Sheffield MP and former Deputy Prime Minister Nick Clegg – claim the Government’s response to the crisis does not go far enough and must include “immediate steps” to tackle overcrowding.

The dispute comes amid growing concerns about rising prison populations and staffing cuts, which have been blamed for an increase in violence, drug use and suicide among inmates.

According to the latest Ministry of Justice figures, the number of serious assaults in prisons has more than doubled over the last decade – going from just under 1,500 in 2007 to 3,372 in 2016.

It also coincides with an undercover investigation by the BBC, which revealed widespread drug use and serious security breaches in a privately-run prison in the North East.

The Panorama report, due to air tonight, found that staff at HMP Northumberland were sometimes left on their own to manage large groups of inmates and often felt unable to confront prisoners for fear that back-up would take too long to arrive.

Speaking at the headquarters of the Centre for Social Justice, Ms Truss acknowledged that “re-offending rates are too high and our prisons are too violent”.

But she dismissed concerns that the prison population as a whole is too high, as she indicated current prisoner numbers are a sign that “the criminal justice system has got better at catching and convicting criminals who have perpetrated some of the appalling crimes”.

“Reductions by cap or quota, or by sweeping sentencing cuts are not a magic bullet, they are a dangerous attempt at a quick fix,” Ms Truss said.

“I want to see the prison population go down because Her Majesty’s Prison and Probation service has got better at reforming offenders... I want to see it go down because we have got better at managing the prison population inside our jails.”

However, Mr Clegg, who has previously called for prison numbers to be slashed from 85,000 to 45,000, warned that the MoJ’s proposals will “take many years to bring about”.

He called for the Justice Secretary to take “concrete steps” to reduce overcrowding. adding that this could be achieved “without changing sentencing practice”.

“The failure of successive governments to tackle the crisis in our jails is locking the country into an entirely avoidable cycle of crime,” he said.

“No meaningful rehabilitation can take place under these conditions. As a consequence, prisons are incubating crime instead of reducing it.

“If the Secretary of State hopes that prisons can pull themselves up by their bootstraps and reduce numbers without the need for hard policy choices, then she is mistaken.

“We need to see immediate steps to alleviate overcrowding together with a long-term plan for a smaller, more sustainable and effective prison system.”